common/inet/inet_net_ntop.c

/*
 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 1996,1999 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static const char rcsid[] = "$Id: inet_net_ntop.c,v 1.5 2006/06/20 02:50:14 marka Exp $";
#endif

#include "port_before.h"

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "port_after.h"

#ifdef SPRINTF_CHAR
# define SPRINTF(x) strlen(sprintf/**/x)
#else
# define SPRINTF(x) ((size_t)sprintf x)
#endif

static char *   inet_net_ntop_ipv4 __P((const u_char *src, int bits,
                    char *dst, size_t size));
static char *   inet_net_ntop_ipv6 __P((const u_char *src, int bits,
                    char *dst, size_t size));

/*%
 * char *
 * inet_net_ntop(af, src, bits, dst, size)
 *  convert network number from network to presentation format.
 *  generates CIDR style result always.
 * return:
 *  pointer to dst, or NULL if an error occurred (check errno).
 * author:
 *  Paul Vixie (ISC), July 1996
 */
char *
inet_net_ntop(af, src, bits, dst, size)
    int af;
    const void *src;
    int bits;
    char *dst;
    size_t size;
{
    switch (af) {
    case AF_INET:
        return (inet_net_ntop_ipv4(src, bits, dst, size));
    case AF_INET6:
        return (inet_net_ntop_ipv6(src, bits, dst, size));
    default:
        errno = EAFNOSUPPORT;
        return (NULL);
    }
}

/*%
 * static char *
 * inet_net_ntop_ipv4(src, bits, dst, size)
 *  convert IPv4 network number from network to presentation format.
 *  generates CIDR style result always.
 * return:
 *  pointer to dst, or NULL if an error occurred (check errno).
 * note:
 *  network byte order assumed.  this means 192.5.5.240/28 has
 *  0b11110000 in its fourth octet.
 * author:
 *  Paul Vixie (ISC), July 1996
 */
static char *
inet_net_ntop_ipv4(src, bits, dst, size)
    const u_char *src;
    int bits;
    char *dst;
    size_t size;
{
    char *odst = dst;
    char *t;
    u_int m;
    int b;

    if (bits < 0 || bits > 32) {
        errno = EINVAL;
        return (NULL);
    }

    if (bits == 0) {
        if (size < sizeof "0")
            goto emsgsize;
        *dst++ = '0';
        size--;
        *dst = '\0';
    }

    /* Format whole octets. */
    for (b = bits / 8; b > 0; b--) {
        if (size <= sizeof "255.")
            goto emsgsize;
        t = dst;
        dst += SPRINTF((dst, "%u", *src++));
        if (b > 1) {
            *dst++ = '.';
            *dst = '\0';
        }
        size -= (size_t)(dst - t);
    }

    /* Format partial octet. */
    b = bits % 8;
    if (b > 0) {
        if (size <= sizeof ".255")
            goto emsgsize;
        t = dst;
        if (dst != odst)
            *dst++ = '.';
        m = ((1 << b) - 1) << (8 - b);
        dst += SPRINTF((dst, "%u", *src & m));
        size -= (size_t)(dst - t);
    }

    /* Format CIDR /width. */
    if (size <= sizeof "/32")
        goto emsgsize;
    dst += SPRINTF((dst, "/%u", bits));
    return (odst);

 emsgsize:
    errno = EMSGSIZE;
    return (NULL);
}

/*%
 * static char *
 * inet_net_ntop_ipv6(src, bits, fakebits, dst, size)
 *  convert IPv6 network number from network to presentation format.
 *  generates CIDR style result always. Picks the shortest representation
 *  unless the IP is really IPv4.
 *  always prints specified number of bits (bits).
 * return:
 *  pointer to dst, or NULL if an error occurred (check errno).
 * note:
 *  network byte order assumed.  this means 192.5.5.240/28 has
 *  0x11110000 in its fourth octet.
 * author:
 *  Vadim Kogan (UCB), June 2001
 *  Original version (IPv4) by Paul Vixie (ISC), July 1996
 */

static char *
inet_net_ntop_ipv6(const u_char *src, int bits, char *dst, size_t size) {
    u_int   m;
    int b;
    int p;
    int zero_s, zero_l, tmp_zero_s, tmp_zero_l;
    int i;
    int is_ipv4 = 0;
    unsigned char inbuf[16];
    char outbuf[sizeof("xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:255.255.255.255/128")];
    char    *cp;
    int words;
    u_char  *s;

    if (bits < 0 || bits > 128) {
        errno = EINVAL;
        return (NULL);
    }

    cp = outbuf;

    if (bits == 0) {
        *cp++ = ':';
        *cp++ = ':';
        *cp = '\0';
    } else {
        /* Copy src to private buffer.  Zero host part. */
        p = (bits + 7) / 8;
        memcpy(inbuf, src, p);
        memset(inbuf + p, 0, 16 - p);
        b = bits % 8;
        if (b != 0) {
            m = ~0 << (8 - b);
            inbuf[p-1] &= m;
        }

        s = inbuf;

        /* how many words need to be displayed in output */
        words = (bits + 15) / 16;
        if (words == 1)
            words = 2;

        /* Find the longest substring of zero's */
        zero_s = zero_l = tmp_zero_s = tmp_zero_l = 0;
        for (i = 0; i < (words * 2); i += 2) {
            if ((s[i] | s[i+1]) == 0) {
                if (tmp_zero_l == 0)
                    tmp_zero_s = i / 2;
                tmp_zero_l++;
            } else {
                if (tmp_zero_l && zero_l < tmp_zero_l) {
                    zero_s = tmp_zero_s;
                    zero_l = tmp_zero_l;
                    tmp_zero_l = 0;
                }
            }
        }

        if (tmp_zero_l && zero_l < tmp_zero_l) {
            zero_s = tmp_zero_s;
            zero_l = tmp_zero_l;
        }

        if (zero_l != words && zero_s == 0 && ((zero_l == 6) ||
            ((zero_l == 5 && s[10] == 0xff && s[11] == 0xff) ||
            ((zero_l == 7 && s[14] != 0 && s[15] != 1)))))
            is_ipv4 = 1;

        /* Format whole words. */
        for (p = 0; p < words; p++) {
            if (zero_l != 0 && p >= zero_s && p < zero_s + zero_l) {
                /* Time to skip some zeros */
                if (p == zero_s)
                    *cp++ = ':';
                if (p == words - 1)
                    *cp++ = ':';
                s++;
                s++;
                continue;
            }

            if (is_ipv4 && p > 5 ) {
                *cp++ = (p == 6) ? ':' : '.';
                cp += SPRINTF((cp, "%u", *s++));
                /* we can potentially drop the last octet */
                if (p != 7 || bits > 120) {
                    *cp++ = '.';
                    cp += SPRINTF((cp, "%u", *s++));
                }
            } else {
                if (cp != outbuf)
                    *cp++ = ':';
                cp += SPRINTF((cp, "%x", *s * 256 + s[1]));
                s += 2;
            }
        }
    }
    /* Format CIDR /width. */
    sprintf(cp, "/%u", bits);
    if (strlen(outbuf) + 1 > size)
        goto emsgsize;
    strcpy(dst, outbuf);

    return (dst);

emsgsize:
    errno = EMSGSIZE;
    return (NULL);
}

/*! \file */